HOUSTON — Lance Armstrong is one of the favorite sons of Texas and a model citizen known as much for his social conscience as his cycling. So it came as a surprise when it was revealed this week that he is one of the biggest individual users of water in Austin, where he lives.

Say it ain’t so, Lance.

In July, Mr. Armstrong, who won the Tour de France seven times, used a whopping 330,000 gallons of water at his lush Spanish-colonial home, with an acre of gardens and a swimming pool, city water authority officials said.

This tremendous flow of H2O, which is 38 times what the average household in the city uses in the summer, comes as Texas is going through a dry spell and officials are asking people to cut back on watering their lawns. “We are definitely short on rain,” Lisa Rhodes, a spokeswoman for the authority, said with a sigh.

Mr. Armstrong declined to be interviewed. He has been in Colorado and California all summer and only noticed the surge in water use when he saw his bills go up, his spokesman, Mark Higgins, said in an e-mail message. (The bill for July was $2,460.) “Lance and all the folks involved are looking into it and will for sure get it under control,” Mr. Higgins wrote.

The Austin American-Statesman, which broke the story on Friday, quoted Mr. Armstrong as saying he was unaware his water use was so high. “I’m a little shocked,” he told The Statesman. “There’s no justification for that much water.” He added, “I need to fix this.”

But city water records suggested that his home has long been a guzzler of water, using an average of 158,000 gallons a month since January 2007. Then, in June, the cyclist shot ahead of the pack, topping the city’s list of residential water users for the first time, officials said. That month his house and garden drank up 222,900 gallons.

Daryl Slusher, an assistant director of the Austin City Water Authority in charge of conservation, said the city had ruled out a leak. Mr. Slusher offered to scrutinize Mr. Armstrong’s irrigation system and perhaps recommend native species that require less water.

Getting Mr. Armstrong on board with water conservation would be a public-relations boon, Mr. Slusher said, although it was a disappointment that Mr. Armstrong had ended up on the top of the city’s water-gluttons list.

“I was surprised he was No. 1,” Mr. Slusher said. “But his response is very encouraging.”